Studies on the structure of the group-specific carbohydrate isolated from Group B streptococcus have shown that this complex polysaccharide contains a large amount of glucitol, an alditol present in all strains of Group B streptococcus analyzed but in no other hemolytic streptococci. Studies are in progress to determine whether the Group B polysaccharide has the same polyrhamnose backbone common to the Group A, A-variant and C polysaccharides. The composition of the Group B polysaccharide suggests this possibility. During the course of these studies, a simple and highly sensitive gas chromatographic procedure was developed for analyzing the carbohydrate composition of whole bacterial cells. Chromatographic tracings of these carbohydrate compositions provide highly characteristic fingerprints of the hemolytic streptococci. The method has been used to analyze single colonies from a blood agar plate.